Patent GB-190218747-A (GB)
Title: Improvements in Automatic Telephone Exchange Mechanism.
Inventor: HADDAN REGINALD
Filed: 1902-08-26
Granted: 1903-04-23
Abstract: 18,747. Haddan, R., [Strowger Automatic Telephone Exchange]. Aug. 26. Telephone systems.-Relates to automatic telephone exchanges for use in large exchanges of ten thousand or more subscribers. The electrical connections of the switches are such that the latter are arranged relatively in several groups of which, in the first group, there is one switch for each subscriber, the switches in this group being termed first selectors. The switches in the second group are termed second selectors, and in number are usually not more than 10 per cent. of the number of switches in the first group. The switches in the third group are termed connectors, and are usually less in number than the number of switches in the firstnamed group, and may be equal in number to the number of switches in the second-named group. The several groups of both selectors and connectors may each be subdivided into secondary groups or sections, as may be desired. Fig. 1 is a front elevation of one of either the first or second selectors, and Fig. 2 is a side elevation of the same. The frames 1 of both the selectors and connectors are the same, and there is, in common, a vertically-disposed step-by-step sliding rotative main switch shaft 2, mounted on the frame, and this shaft is provided with switch arms 3, 4, 5 which, by virtue ot the step-by-step sliding rotative motion of the shaft, are adapted to contact anyone of two banks 6, 7 of contact-points, which are arranged preferably in concave rows, Fig. 1. The step-bystep rotative motion is imparted to the main switch shaft 2 by an electromagnet 8, which operates a long ratchet-wheel 9 through a lever 10 and pawl 11. The step-by-step longitudinal movement of the shaft 2 is accomplished by the action of a vertical electromagnet 12, which operates a cylindrical ratchet 13 through a vertical magnet lever 14 and pawl 15. The shaft 2 is successively lifted step by step against gravity, and is rotated against the resilience of a spring 16 connecting the lower end with the frame, as shown in Figs. 1 and 2, the downward movement of the shaft being limited at its normal position by a collar 17, or any other suitable device contacting with the frame, and the normal rotary position is maintained by a pin 18, which contacts with a pin 19 projecting from the top of the frame. A small short pin 20, Figs. 1 and 2, in the top of the frame will be contacted by the pin 18 and hold the shaft in the initial position, if an effort is made to rotate it until after one vertical step movement is completed. There is a double detent having one arm 21 adapted to engage the circular teeth of the cylindrical ratchet 13, and another arm 22 for engaging the teeth of the ratchet-wheel 9, the two detents being yieldingly held in engagement with the ratchets by the spring 23. The shaft 2 is provided with means which prevent any further vertical movement after the shaft has been rotated one step, and which comprise a stationary detent 24 which is secured to the frame 1, Fig. 1, into which the point of the detent takes. The point of the stationary detent 24 will remain in a groove so long as shaft 2 is only moved step by step vertically, but if it is moved but one rotative step, the point of the detent engages in a groove between two teeth of the cylinder ratchet 13, and although it permits the shaft to rotate further, then prevents any longitudinal or vertical movement either way, thus preventing the switch arms 3, 4, 5 from being bent or injured when in engagement with any of the concave rows of contact-points, so that, in order to reach any particular row of contact-points, a vertical step-by-step movement must first be made to the particular row wanted, and when the particular contact-point is found in the row the operation of the :release must first cause the shaft to reverse its motion in a rotary direction, so that the switch arms 3, 4, 5 are clear of the contact points, and the detent 24 is in the groove before the shaft 2 falls to the initial position shown in Figs. 1 and 2. The auxiliary switch in both the selectors and connectors, in this instance, comprises five switch arms 26, 27, 28, 29, and 30, which are insulatingly secured at one end to an arm 31 on the shaft 32 mounted at the ends in the frame 1. The switch arms 26 ... 30 are normally in engagement with five insulated contactpoints 33, 34, 35, 36, 37, but are adapted by springs 38 on the shaft 32 to be disengaged from those points and be placed in connection with five other insulated contact-points. Thus far, the selectors and connectors are alike, but the five auxiliary switch arms of both the first and second selectors are not held by the same means in engagement with the contacts 33 ... 37 in the normal position, nor are they caused to be disengaged or to engage contacts 39 ... 43 (not shown) by the same means as in the connectors ; this constitutes the real difference in the construction between the connectors and selectors, with the exception of the ringing-magnet attached to the connector switch. In the release mechanism, shown in Fig. 1, of both the selectors and connectors, there is a short arm or crank attached to the upper end of the shaft 32, and at the outer end of this crank is pivotally secured the end of a bent connecting-rod, which extends across to the opposite side of the main frame, where its slotted end is in engagement with an arm 52 of the double detent 21. 53 is the release electromagnet, the armature 54 of which is pivotally attached at one end to the frame 1, and is held out of contact by means of a spring 55. Firmly attached at one end to the outer end of the armature 54 is a release lock spring which extends across to the opposite side of the main frame, and at the outer end of this spring is a hole disposed so as to engage with a projection from the double detent 21. In the connectors, the auxiliary switch magnet 48 carries a catch spring having a shoulder at the top end similar to the hook spring 46, Fig. 2, of the selectors, and a rigid armature arm, having a bent outer end portion, which contacts with the catch spring as shown. In both the selectors and connectors, a short release arm, bent at a right-angle at the outer end, is disposed so as to be in contact with the outer surface of the pawl 15 of the vertical lever 14, to hold the pawl out of engagement with the cylindrical ratchet 13, when the lever 14 is in the initial position shown in Fig. 2. The source of current for operating the vertical, rotary, release, and auxiliary switch magnets, and for ringing the signal bells, is supplied at the central station, as shown in the diagrammatic views 33, 34. The shaft of the motor is extended so as to have mounted thereon commutators 86, 87, 88, 89, of which each consists, in this instance, of a cylindrically-shaped rotative part ; the commutators 86, 87, 88 are mounted on the insulated metal sleeve 90, and 89 on the sleeve 91. In each of the commutators one-half of the peripheral surface consists of electric conducting-material connected with the metal sleeves, and the other half is of insulating-material. The sleeve brush 92 connects the sleeve 90 with the wire 106 from the grounded side of the battery 65, while the brushes 93, 94, and 95, respectively, connect with wires 96, 97, and 98, of which the wires 96, 97 are in the ringing or signal circuit, and, for this reason, commutators 86, 87 are relatively mounted on the sleeve 90, so as alternately to make and break the current over the signal wires 96, 97. The brush 95 connects with the wire 98, which leads to the secondary of the induction coil 99 and thence to main side of the battery 65 through the wire 100. The sleeve brush 101 connects through the wire 102 to the wire 100, and the commutator brush 103 connects to the wire 104, which leads to the rotary magnets 8. At 105 is an incandescent lamp serving as a resistance in what is termed the private wire 108, from the main side of battery, and leading to the auxiliary magnet 48. Referring to Figs. 33 and 34, in calling subscriber No. 3333 at station F, Fig. 34, from the subscriber's station No. 3331 at section A, Fig. 33, the signal key 131 is depressed three times, which makes and breaks connection three times between the ground 129 and wire 133, when current flows through the line wire 110 and relay magnet 74 of the first selector, section B, Fig. 33, wire 153, then through the auxiliary switch arm 27, contact-point 34, wire 113, retardation magnet 72, wire 100, battery 65, and ground 106, and thereby energizing the relay magnet 74 and closing the local circuit by contacting springs 137, 112, when local circuit current flows through the vertical magnet 12, contact-point 37, auxiliary switch arm 30, wire 100, battery 65, ground wire 106, auxiliary switch arm 28, contact-point 35, and spring 112, and each time the vertical magnet 12 is energized, the main switch shaft 2 is moved up one step, and held in such moved position by the engagement of the detent 21 with the cylinder ratchet 13, the main switch arms 3, 4, 5 being thus carried up three steps, when they are in position, by virtue of a step-by-step movement, to engagement with a row of contact-points in the third concave rows of the banks 6, 7, Fig. 1, which are adapted to connect with a group of second selectors designated by the number 3000. The second signal key 130 at sub-station 3331, section A, Fig. 33, is depressed once, which makes and breaks connection between the wire 132 and ground wire 129, when current flows through the wire 109 to the relay magnet 75 of the first selector, section B, Fig. 33, and then the wire 154, auxiliary switch 26, contact-point 33, wire 111, retardation magnet 73, wire 100, battery 65, ground wire 106, thereby operating the relay magnet 25 and closing the local battery circuit through the contact-spring 112. 138 when local current flows through the wire 155, rotary magnet 8, wire 104, then in section G, commutator brush